JP2733596B2 - Data erasing method in data storage device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a portable data storage device such as an electronic notebook, an electronic memo, a pocket computer, etc.
The present invention relates to a method of erasing infrequently used data in spite of the elapsed period.

[0002]

2. Description of the Related Art FIG. 6 is a block diagram showing a schematic electrical configuration of a conventional portable data storage device.

[0003] In the figure, reference numeral 1 denotes a CP that controls the overall control.
U and 2 are ROs storing programs for control.
M, 3 are RAM as working memory, 4 is RAM
Reference numeral 3 denotes a backup power supply, 5 is a key input device, and 6 is a display device such as a liquid crystal display panel.

Data (for example, an address book or a telephone number) input by the key input device 5 while being displayed on the display device 6 is written into the RAM 3 by a write command operation on the key input device 5.

In the RAM 3, as shown in FIG.
A large number of sequentially input data are represented by D ₁ , D ₂ , D _3.
D _n , D _{n + 1} ... Are stored.

As the number of uses of the data storage device increases, the number of data stored in the RAM 3 also increases. However, the storage capacity of the RAM 3 naturally has a certain limit. Therefore, unless the old data is deleted, new data to be registered next cannot be stored.

[0007] Therefore, the user searches for a data that is considered to be erasable from a data group already stored. The search is performed by temporarily checking the title list of the data, and displaying the data on the display device 6 to check whether the data is unnecessary data that may be actually deleted. Take a look. If the data is hardly used in the past and is unnecessary and can be deleted, the user performs a deletion instruction operation using the key input device 5. Then, the CPU 1 erases the data designated to be erased from the RAM 3. If the data should not be deleted, continue the work and
Search for data that can be deleted.

[0008]

As described above, in the conventional data storage device, the number of registered data increases cumulatively with the number of uses unless the user intentionally deletes the data. As the area that can be stored gradually decreases, new data cannot be registered in the end.

Therefore, as described above, data deemed unnecessary is deleted according to the user's will. However, it is extremely troublesome and time-consuming to find unnecessary data that can be deleted from a large number of registered data. It has to be work. In addition, there is a possibility that data that is frequently used and should not be deleted may be deleted due to some misunderstanding or erroneous operation.

[0010] The present invention has been made in view of such circumstances, and unnecessary data (data that is infrequently used for an elapsed period) is automatically generated without depending on the user's intention or work. The purpose is to free the user from the troublesome work of erasing unnecessary data.

[0011]

According to a data erasing method for a data storage device according to the present invention, the number of uses of each data is counted up and stored for each of a plurality of data registered in a memory. The date when each data was used most recently (the latest use date) is stored, and the difference between the present and the latest use date is calculated for each data. If the difference period is equal to or longer than a predetermined period, the date is used. The number of usage counts of data is divided by the difference period, and when the result of the division is equal to or less than a predetermined value, the data is automatically deleted from the memory.

[0012]

The data in which the difference between the present date and the latest use date is less than the predetermined period is registered and stored as it is. For data for which the difference period is longer than the specified period,
The [use count number] / [difference period] is compared with a predetermined value, and data exceeding the predetermined value is registered and stored as it is, but data less than the predetermined value is used less frequently for the elapsed period. So it is automatically erased from memory.

When a reset operation for erasing all data registered in the memory is performed so that time information at the time of the reset operation is stored in the memory, the all clear date and time can be referred to. It is possible to estimate what is the cause of the total erasure of the stored contents.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a data erasing method in a data storage device according to the present invention will be described in detail.

FIG. 1 is a block diagram showing an electrical configuration of a portable data storage device.

In the figure, reference numeral 11 denotes a CP that controls the entire control.
U and 12 are ROs storing programs for control.
M, 13 are RAM as working memory, 14 is R
Reference numeral 15 denotes a backup power supply for the AM 13, reference numeral 15 denotes a key input device, reference numeral 16 denotes a display device such as a liquid crystal display panel, reference numeral 17 denotes a clock device (timer), and reference numeral 18 denotes a data source. Timing device 1
7 is clocked in units of year, month, day, hour, minute, and second. However, in the data erasing operation to be described later, the calculation in the unit of date is sufficient.

When registering data in the RAM 13, an arbitrary material in the material source 18 may be read and registered by a read command operation in the key input device 15, or may be registered by a key input operation in the key input device 15.
In some cases, the material is created by the PU 11 itself and registered in the RAM 13.

When registering this data, the CPU 11
The time information (year / month / day / hour / minute / second) is read out from the clock device 17 and registered in the RAM 13 with the time information attached to the data.

At the same time, "0" is registered as a usage count number. Such registration of data integrated with the time information and the usage count of “0” is performed for each individual data.

Each data can be read out by a reading operation with the key input device 15 and displayed on the display device 16. Each time the CPU 11 reads and displays the data, the CPU 11 counts up the number of uses of the data by +1 and updates and stores the time information at that time in the RAM 13 as the latest use time information instead of the original time information. become.

FIG. 2 shows an example of a data format in the RAM 13. Data D ₁ , D ₂ , D ₃ , D ₄ , D
₅ are registered in this order.

[0022] The time information T ₁₅ and the usage count the number of times for the data D ₁ "5", the date on which the data D ₁ has been used in the latest (use the latest date) is T _15, moreover, after being first registered , The fifth use.

[0023] The time information T ₂₂ and the usage count the number of times of the data D _{2 "2"} is, use the latest date of the data D ₂ is T _22, and, after it has been initially registered, was in use for the second time It shows that.

[0024] The time information T ₃₀ and the usage count the number of "0" for the data D _3, the data D ₃ has never been utilized from when it is first registered, the date of the registration is T ₃₀
And the usage count number remains “0”.

[0025] The time information T ₄₃ and the usage count the number of times for the data D ₄ "3" is, use the latest date of the data D ₄ is T _43, and, after it is first registered, there in the use of the third round It shows that.

[0026] The time information T ₅₀ and the usage count the number of "0" for the data D _5, the data D ₅ has never been utilized from when it is first registered, the date of the registration is T ₅₀
And the usage count number remains “0”.

Note that the RAM in such a format is used.
The state of storage at 13 is maintained by the backup power supply 14 even if the main power supply is turned off.

Next, an operation for erasing data that is infrequently used for an elapsed period will be described with reference to the flowchart of FIG.

This operation is performed every time the main power supply is turned on. Step S by turning on the main power
The operation from 1 is started. The CPU 11 determines in step S
At 1, the data number N is initialized to "1". In step S2, stores the usage latest date T _NX data D _N of the data number N is read from the RAM13 into the register. In step S3, the current date T ₀ and the latest use date T
The difference from _NX is calculated and stored in a register as the difference period T _DIF (T _DIF = T ₀ −T _NX ).

Next, in step S4, the difference T
_DIF determines whether a predetermined time period A ₀ or more. If the difference period T _DIF is less than the predetermined period A ₀ , since the data has been used within the period of A ₀ , the data D _N is not erased, and the process skips to step S 9. I do.

However, when the difference period T _DIF is _equal to or longer than the predetermined period A ₀ , the predetermined period A ₀ has already elapsed since the latest use, and the time period D ₀ is used once during the period A _0. That was not done. At this time,
Proceed to step S5, and stores the usage count number U _NX data D _N of the data number N in the register is read out from the RAM 13.

Next, in step S6, the usage count U _NX is divided by the difference period T _DIF , and the result of the division is α _N
(Α _N = U _NX / T _DIF ).
In step S7, the division result alpha _N determines whether it is ₀ or less than a predetermined value beta. When the predetermined value β ₀ is exceeded,
Although it has been utilized within the period of A ₀ that the current goes back from there in no once data, because it is a relatively high data use frequency, erasing data D _N is not performed, skip to step S9 .

However, when the division result α _N is equal to or smaller than the predetermined value β ₀ , the data has never been used within the period of A ₀ , which is farther from the present time, and the data has been used less frequently. become. It is assumed that such data will not be used again and will be deleted. That is, the process proceeds to step S8, automatically erase the data D _N of the data number N from the RAM 13.

In step S9, it is determined whether or not the determination for all data has been completed. If not, the flow advances to step S10 to increase the data number N by +.
After incrementing by one, the process returns to step S2 to perform the same processing for the next data. By repeating such a process, it is determined that the device has never been used within the predetermined period A ₀ and that the frequency of use before the predetermined period A ₀ is sufficiently low (U _NX / T _DIF ≦ β ₀ ). The erased data is automatically deleted from the RAM 13.

When the above-mentioned determination for all data is completed, the process proceeds to the main routine.

Instead of performing the operation from step S1 when the main power supply is turned on, the operation may be performed by selecting an unnecessary data erasing mode at a user's will at any time.

A specific example will be described with reference to FIG.

Here, six months, that is, A ₀ = 180 days are set as the predetermined period A ₀ , and the predetermined value β ₀ is
It is assumed that β ₀ = 0.009 is set.

The data D ₁₀₀ was used most recently.
It is 365 days before the current date. It has been used four times since it was first registered. T _DIF = 36
5, and U ₁₀₀ = 4. Therefore, α ₁₀₀ = 4
/365≒0.011, which is β ₀ = 0.00
Compared to 9, because it is alpha _100> beta _0, data D _{10 0}
Are kept registered in the RAM 13.

The data D ₂₀₀ was also used most recently.
It is 365 days before the current date. It has been used twice since it was first registered. T _DIF = 36
5 and U ₂₀₀ = 2. Therefore, α ₁₀₀ = 2
/365≒0.005, which is β ₀ = 0.00
Compared to 9, because it is alpha ₂₀₀ <beta _0, data D _{20 0}
Is erased from the RAM 13.

The data D ₃₀₀ was used most recently.
It is 200 days before the current date. It has been used twice since it was first registered. T _DIF = 20
0 and U ₃₀₀ = 2. Therefore, α ₃₀₀ = 2
/200=0.010, which results in β ₀ = 0.00
9, since α ₃₀₀ > β ₀ , the data D _{30 0}
Are kept registered in the RAM 13.

The data D ₄₀₀ was also used (displayed) most recently 200 days before the current date. And it has not been used even once since it was first registered.
A T _{DI F} = 200, an U ₄₀₀ = 0. Therefore, α ₄₀₀ = 0/200 = 0.000, which is
Since α ₄₀₀ <β _{0 as} compared with β ₀ = 0.009, the data D ₄₀₀ is erased from the RAM 13.

The calculation of the difference period T _DIF may be performed in units of year, month and day, or in units of year, month and day, or in units of year, month, day and time.

In a data storage device having a memory capable of storing a large number of data (address book, telephone number, etc.), a memory reset switch for so-called one-shot erasure is provided. This memory reset switch is first operated before shipment after the test in the production stage is completed, but may be actively operated according to the user's will.

As causes for erasing all the stored contents of the memory, in addition to the operation of the memory reset switch,
This may be due to the disappearance of the backup at the time of battery replacement, or to a hardware failure such as static electricity, noise, or the disconnection of a memory lead. Also, if the user accidentally operates the memory reset switch, all the stored contents are naturally erased.

Therefore, it is necessary to estimate the cause of the erasure of all the stored contents. As a countermeasure, it is conceivable to store the date and time when a memory reset operation is performed. This measure will be described with reference to FIG.

In FIG. 5, 21 is a CPU and 22 is a RO.
M and 23 are RAMs, 24 is a backup power supply, 25 is a key input device, 26 is a display device, 27 is a gate array,
8 is a real-time clock, 29 is a memory reset switch.

Assume that some data is registered in the RAM 23. An operation when the stored contents of the RAM 23 are entirely erased from this state will be described.

First, the memory reset switch 29 is pressed and operated. The signal is sent to the CPU via the gate array 27.
21 and the CPU 21 ends the operation currently being executed. Then, the CPU 21 displays on the display device 26 a message confirming that all stored contents are to be erased, and waits for a key input.
When the memory erase key of the key input device 25 is pressed, the RAM 23 is all cleared and initialized, and the date and time data at the time of all clear are read from the real time clock 28 via the gate array 27 and the RAM 2 is reset.
Write to 3. Next, an initial screen is displayed.

When all the stored data have been lost, the all clear date and time stored in the RAM 23 is referred to when estimating the cause. When the all-clear date and time is a time of the production stage, a time of replacement of the backup power supply 14, or a time when it is completely unexpected, it is not due to an operation mistake such as a carelessness of the user. It can be presumed to be caused by an unexpected factor or a defective set. Alternatively, it can be estimated that the storage contents are completely erased due to static electricity or noise, or the storage contents are completely erased due to a hardware failure such as a connection failure of the external lead of the RAM 23. Then, appropriate measures such as repair can be taken.

On the other hand, when the all clear date and time is relatively recent, not at the stage of production or at the time of replacement of the backup power supply 14, it can be estimated that an operation error by the user is a cause of the total erasure of the stored contents.

Although the real-time clock 28 has been used for writing the date and time, any other data may be used.
The RAM 23 (main storage device) is used to write the date and time. Alternatively, a dedicated memory element or register may be used.

[0053]

As described above, according to the present invention, data that is infrequently used in spite of the elapsed time is automatically deleted from the memory as unnecessary data. It can be released from data erasing work. By erasing the unnecessary data, an area for storing new data is always secured, so that the memory can be used effectively.

At the time of a reset operation for erasing all data,
If the time information at the time of the reset operation is configured to be stored in the memory, it is useful for estimating whether the cause of the erasure of the stored contents is a user operation error or not by referring to the all clear date and time. be able to.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electrical configuration of an embodiment of a data erasing method in a data storage device according to the present invention.

FIG. 2 is a memory format in the data storage device of the embodiment.

FIG. 3 is a flowchart for explaining the operation of the embodiment.

FIG. 4 is an explanatory diagram of a specific operation example of the embodiment.

FIG. 5 is a block diagram showing an electrical configuration of a data storage device according to another embodiment.

FIG. 6 is a block diagram showing an electrical configuration of a conventional data storage device.

FIG. 7 is a memory format in a conventional data storage device.

[Explanation of symbols]

 11, 21 CPU 12, 22 ROM 13, 23 RAM 14, 24 Backup power supply 15, 25 Key input device 16, 26 Display device 17 Timing device 27 Gate array 28 Real-time clock 29 Memory reset switch

Claims (2)

(57) [Claims] 1. For each of a plurality of data registered in a memory, the number of uses of each data is counted up and stored, and a date when each data is used latest (use latest date) is stored. In addition, the difference between the present date and the latest use date is calculated for each data, and when the period of the difference is equal to or longer than a predetermined period, the number of use counts of the data is divided by the period of the difference, and the division result There when equal to or less than the predetermined value, the data erasing method in a data storage device, characterized in that the data to be automatically erased from the memory. 2. A data erasing method in a data storage device, wherein at the time of a reset operation for erasing all data registered in a memory, time information at the time of the reset operation is stored in the memory.